Fire detection system

Abstract

Comprehensive system for fire detection and implementing thereof. The disclosed system combines and optimizes optical, electrical, and sensor sub-systems to provide the functionality demanded by the market. While many of the individual functions exist separately, none of the existing products combine elements from different sub-systems to provide a much higher level of functionality. The present disclosure shows how to build a very compact housing around the smoke detector while keeping the reflections from the housing structure to a very low value while satisfying all the other peripheral needs of fast response to smoke and preventing ambient light. This allows very small measurements of light scattering of the smoke particles to be reliable in a device resistant to the negative effects of dust.

What is claimed is: 
     
       1. An apparatus for detecting smoke within a compact footprint detector which compensates the deleterious effects of dust, thereby increasing longevity and efficacy, the apparatus comprising:
 a first light source; 
 a first photodetector disposed proximate to the first light source; and 
 a digital circuit for performing:
 receiving a first signal from the first photodetector, the first signal is based on light which has been scattered from the first light source; 
 performing a baseline factory measurement of light with no particulate matter present; 
 performing an in-situ measurement; 
 periodically performing an automatic self-calibration test comparing the baseline factory measurement with the in-situ measurement of light; 
 calibrating the apparatus for detector smoke using the automatic self-calibration test result; and, 
 determining a presence of smoke and a type of smoke at least based on the first received signal and calibration, wherein the type of smoke is determined based on an average angle of the light being scattered in the first received signal; 
 wherein the first photodetector is configured to receive no direct light from the first light source. 
 
 
     
     
       2. The apparatus according to  claim 1  further comprising a septum disposed between the first photodetector and the first light source. 
     
     
       3. The apparatus according to  claim 1  further comprising an optical reflective element configured to reflect light from the first light source towards the first photodetector. 
     
     
       4. The apparatus according to  claim 3  wherein the optical reflective element has a profile shaped like a conic section. 
     
     
       5. The apparatus according to  claim 4  wherein the conic section is a parabola. 
     
     
       6. The apparatus according to  claim 4  wherein the conic section is an ellipse. 
     
     
       7. The apparatus according to  claim 1  wherein the first light source is an LED. 
     
     
       8. The apparatus according to  claim 1  wherein the digital circuit further performs time-based filtering. 
     
     
       9. The apparatus according to  claim 1  further comprising a second light source and second photodetector. 
     
     
       10. The apparatus according to  claim 9  wherein the determination of the presence of smoke includes calculating a ratio from signal received from the first and second photodetectors. 
     
     
       11. The apparatus according to  claim 1  further comprising a cap. 
     
     
       12. The apparatus according to  claim 11  wherein the cap has a refractive index between 1.4-1.7. 
     
     
       13. The apparatus according to  claim 12  wherein the cap is lossy. 
     
     
       14. A method for detecting smoke within a compact footprint detector which compensates the deleterious effects of dust, thereby increasing longevity and efficacy, the method comprising:
 emitting light from a first light source; 
 receiving the light which has been scattered from a first photodetector disposed proximate to the first light source; and 
 receiving a first signal from the first photodetector; 
 performing a baseline factory measurement of light with no particulate matter present; 
 performing an in-situ measurement; 
 periodically performing an automatic self-calibration test comparing the baseline factory measurement with the in-situ measurement of light; 
 calibrating the apparatus for detecting smoke using the automatic self-calibration test result; and, 
 determining a presence of smoke and a type of smoke at least based on the first received signal and calibration, wherein the type of smoke is determined based on an average angle of the light being scattered in the first received signal; 
 wherein the first photodetector is configured to receive no direct light from the first light source. 
 
     
     
       15. The method according to  claim 14  further comprising blocking light which can directly propagate between the first photodetector and the first light source. 
     
     
       16. The method according to  claim 15  further comprising using a septum disposed between the first photodetector and the first light source to block the light. 
     
     
       17. The method according to  claim 14  further comprising reflecting light from the first light source towards the first photodetector. 
     
     
       18. The method according to  claim 14  further comprising emitting light from a second light source. 
     
     
       19. The method according to  claim 14  further comprising receiving light from at a second photodetector. 
     
     
       20. The method according to  claim 19  further comprising calculating a ratio from signal received from the first and second photodetectors. 
     
     
       21. The method according to  claim 20  further comprising determining the presence of smoke based at least on the calculated ratio. 
     
     
       22. The method according to  claim 14  further comprising performing time-based filtering. 
     
     
       23. An apparatus for detecting smoke within a compact footprint detector which compensates the deleterious effects of dust, thereby increasing longevity and efficacy, the apparatus comprising:
 a first light source; 
 a first photodetector disposed proximate to the first light source; and 
 a digital circuit for;
 receiving a first signal from the first photodetector; 
 performing a baseline factory measurement of light with no particulate matter present; 
 performing an in-situ measurement; 
 periodically performing an automatic self-calibration test comparing the baseline factory measurement with the in-situ measurement of light; 
 calibrating the apparatus for detecting smoke using the automatic self-calibration test result; and, 
 determining a presence of smoke and a type of smoke at least based on the first received signal and calibration, wherein the type of smoke is determined based on an average angle of the light being scattered in the first received signal; 
 
 wherein the first photodetector is configured to receive no direct light from the first light source.